class TongXue:
    """代表一名同学"""
    def __init__(self, name):
        self.name = name
        self._eaten = None
    
    def eat(self, what):
        self._eaten = what
        return None
    
    def what_have_been_eaten(self):
        if self._eaten is None:
            print(f"{self.name} 什么也没有吃.")
        else:
            print(f"{self.name} 刚刚吃了 {self._eaten}.")